Chopping devices for cutting glass filaments are known in the art. For example, U.S. Pat. No. 3,869,268 to Briar et al. teaches a device for chopping continuous glass filaments drawn from streams of molten glass into discrete segments. The device comprises a cot roll and a juxtaposed cutting roll, which together define a cutting nip for receiving the glass filaments. The cot and cutting rolls supply the attenuation forces to draw the streams of molten glass into filaments and further serve to chop the glass filaments into discrete segments. Because the filaments are continuous and pulled by the cot and cutter rolls towards them, conveying or delivering the glass filaments to the cutting nip is generally not a problem. Also, because the filaments are continuous and due to their weight, it is typically not difficult to keep the glass filaments properly positioned between the cot and cutting rolls during the cutting step.
It would be desirable to use a chopping device comprising cot and cutting rolls to cut a light-weight mineral fiber wool tow into discrete sections. However, in order to do so, a conveying system must be designed which is capable of delivering a light-weight tow to a cutting nip between cot and cutting rolls. The system must also be capable of maintaining the light-weight tow properly positioned between the two rolls.
In accordance with the present invention, a conveying system is provided which is capable of delivering a light-weight tow to a cutting nip between cot and cutting rolls.
In accordance with a first aspect of the present invention, a system is provided for forming a continuous mineral fiber wool tow and cutting the tow into discrete lengths. The system comprises a conveying apparatus for pulling a mineral fiber wool tow from a mineral fiber pack at a first location and transporting the tow to a chopping station. A chopping apparatus is positioned at the chopping station for chopping the tow into discrete lengths. The conveying apparatus further receives the discrete lengths at the chopping station and transports the discrete lengths to a collecting station. The conveying apparatus further includes a collection device located at the collecting station for receiving the discrete lengths of mineral fiber wool material and collecting the discrete lengths for subsequent use.
Preferably, the chopping apparatus comprises a cot roll having a generally smooth outer circumferential surface; a drive motor for effecting rotation of the cot roll; a rotatable cutting roll juxtaposed to the cot roll and contacting the cot roll at its circumferential surface to rotate with the cot roll; and a substantially air-tight enclosure surrounding the cot roll and the cutting roll. The rotatable cutting roll and the cot roll define a cutting nip for receiving the tow such that the tow is received in the nip and cut into discrete lengths.
The cutting roll may comprise a cutting wheel having a plurality of cutting blades associated therewith and spaced apart from one another about the cutting wheel.
The conveying apparatus preferably comprises a collection hood for receiving the mineral fiber tow; a nozzle extending into the air-tight enclosure for delivering the tow to the cutting nip; a first conduit section coupled to and extending between the hood and the nozzle; a second conduit section coupled to and extending between the chopping device and the collection device and a vacuum pump associated with the collection device for drawing a vacuum in the collection device, the air-tight enclosure, the nozzle, the first and second conduit sections, and the collection hood.
In one embodiment, the conveying apparatus further comprises a third conduit section coupled to and extending between the collection hood and the second conduit section for defining a bypass path for the tow when the tow is to be conveyed to the collecting station without being cut into discrete lengths. A first valve device may be associated with the first conduit section for allowing the tow to pass through the first conduit section when the first valve device is in its open position and for preventing the tow from passing through the first conduit section when the first valve device is in its closed position. A second valve device may be associated with the third conduit section for allowing the tow to pass through the third conduit section when the second valve device is in its open position and for preventing the tow from passing through the third conduit section when the second valve device is in its closed position.
In accordance with a second aspect of the present invention, a chopping device is provided for cutting a continuous mineral fiber wool tow into discrete lengths. The cutting device comprises a cot roll having a generally smooth outer circumferential surface; a drive motor for effecting rotation of the cot roll; and a rotatable cutting roll juxtaposed to the cot roll and contacting the cot roll at its circumferential surface to rotate with the cot roll. The rotatable cutting roll and the cot roll define a cutting nip for receiving the tow such that the tow is received in the nip and cut into discrete lengths. The cutting roll preferably comprises a cutting wheel having a plurality of cutting blades associated therewith and spaced apart from one another about the cutting wheel. At least one of the cutting blades has a generally V shape, a chevron shape or is formed in the shape of an arc.
In one of the illustrated embodiments, the blades are spaced apart from one another about the cutting wheel such that at least one blade is always in contact with the cot roll during rotation of the cot roll and the cutting roll.
It is further contemplated that the cutting roll may further comprise a plurality of teeth positioned about at least one of the outer circumferential edges of the cutting wheel.
In accordance with a third aspect of the present invention, a method is provided for forming a continuous mineral fiber wool tow and cutting the tow into discrete lengths. The method comprises the steps of: pulling a continuous mineral fiber wool tow from a mineral fiber pack; conveying the tow to a chopping station; chopping the tow into discrete lengths at the chopping station; and transporting the discrete lengths from the chopping station to a collecting station where the discrete lengths are collected for subsequent use.
Accordingly, it is an object of the present invention to provide a conveying system which is capable of delivering a light-weight tow to a cutting nip between cot and cutting rolls. It is further an object of the present invention to provide a conveying system which is capable of maintaining a light-weight tow generally centered between cot and cutting rolls such that the tow is cut into discrete lengths or segments. It is another object of the present invention to provide a method and apparatus for cutting a mineral fiber wool tow into discrete lengths.
These and other objects and advantages of the present invention will be apparent from the following description, the accompanying drawings and the appended claims.